271 research outputs found
Definition of scenarios and modelling of water level for the flooding risk management in the Seine estuary
Water Qualit
Évaluer une pratique d'orientation professionnelle pour adultes: les effets individuels du bilan de compétences
À partir des travaux théoriques et empiriques qui analysent les effets du conseil en orientation, une recherche longitudinale et quasi-expérimentale a été menée en comparant un échantillon de sujets ayant suivi un bilan de compétences à un groupe contrôle. Cette étude porte sur des processus individuels décrits dans plusieurs théories vocationnelles : l'estime de soi, l'auto-connaissance et l'image de soi, les démarches d'engagement et le devenir des bénéficiaires plusieurs mois après l'intervention. Les résultats semblent confirmer les principales hypothèses. La taille de l'effet relevée pour l'ensemble des variables (+ 0.62) est comparable à celle observée dans les travaux nord-américains. La stabilité des effets semble acquise pour deux catégories de variables sur trois malgré une légère décroissance des productions de l'image de soi. Enfin l'intensité du traitement ne semble pas confirmer totalement son statut de variable modératrice, à l'exception de son rôle dans le développement de l'auto-connaissance. La discussion porte sur les perspectives en matière d'évaluation des pratiques d'orientation, ainsi que les considérations théoriques qui méritent d'être développées dans le futur.From theoretical and empirical works analyzing the effects of career counseling, an experimental and longitudinal study has been carried out ; it compares a sample of individuals having undertaken competence assessment with a control group and deals with self-esteem, career maturity, self-concept, individual mobilization and the subjects' situations several months after the intervention. The results correspond to our main hypotheses. The magnitude of the effect calculated for ail the variables (+ 0.62) is similar to the one observed in the meta-analysis concerning the same topic. The stability of effects has also been demonstrated for two out of three categories of variables in spite of a slight decrease in the production of self-concept. Finally, treatment intensity seems to have a lesser effect than the one expected but it strengthens its role in the development of career maturity. The discussion focuses on the prospects for counselling practice assessment, as well as theoretical direction meriting future development
Trans-Planckian Dark Energy?
It has recently been proposed by Mersini et al. 01, Bastero-Gil and Mersini
02 that the dark energy could be attributed to the cosmological properties of a
scalar field with a non-standard dispersion relation that decreases
exponentially at wave-numbers larger than Planck scale (k_phys > M_Planck). In
this scenario, the energy density stored in the modes of trans-Planckian
wave-numbers but sub-Hubble frequencies produced by amplification of the vacuum
quantum fluctuations would account naturally for the dark energy. The present
article examines this model in detail and shows step by step that it does not
work. In particular, we show that this model cannot make definite predictions
since there is no well-defined vacuum state in the region of wave-numbers
considered, hence the initial data cannot be specified unambiguously. We also
show that for most choices of initial data this scenario implies the production
of a large amount of energy density (of order M_Planck^4) for modes with
momenta of order M_Planck, far in excess of the background energy density. We
evaluate the amount of fine-tuning in the initial data necessary to avoid this
back-reaction problem and find it is of order H/M_Planck. We also argue that
the equation of state of the trans-Planckian modes is not vacuum-like.
Therefore this model does not provide a suitable explanation for the dark
energy.Comment: RevTeX - 15 pages, 7 figures: final version to appear in PRD, minor
changes, 1 figure adde
WMAP data and the curvature of space
Inter alia, the high precision WMAP data on Cosmic Microwave Background
Radiation marginally indicate that the universe has positively curved (and
hence spherical) spatial sections. In this paper, we take this data seriously
and consider some of the consequences for the background dynamics. In
particular, we show that this implies a limit to the number of e-foldings that
could have taken place in the inflationary epoch; however this limit is
consistent with some inflationary models that solve all the usual cosmological
problems and are consistent with standard structure formation theory.Comment: 4 pages, 2 figure
Atelier "Vivre en Ville" : modes de vie en périphérie : les pratiques dans les centres commerciaux, modes d'habiter en péri-urbain
Parmi tous les phénomènes de centralité et de périphérie, sources de multiples observations depuis ces dernières décennies, nous avons choisi d'évoquer au cours de la journée d' atelier « Vivre en Ville » du mois de juillet 1999 , deux points précis qui concernent les pratiques et les modes de vie :-dans les centres commerciaux de périphérie en abordant le thème selon trois entrées :•une étude réalisée dans l'agglomération nantaise visant à appréhender les pratiques et les perceptions d'usagers de centres commerciaux,•une approche par I'ETHOLOGIE, visant à étudier les comportements des utilisateurs d'un centre commercial de région parisienne•une entrée par la SEMIOTIQUE permettant de rendre compte des types de parcours des individus dans l'espace commercial-les modes d' habiter en péri-urbain : à partir d'une étude réalisée dans le pays d'Aix qui a permis de mettre en évidence certaines valeurs, certains attributs de ces nouveaux lieux de centralité.Comment vivent les habitants du péri-urbain ? Qu'est-ce qu'ils en pensent ? Qu'est-ce qu'ils en disent ?Quelle est la place du local ? de l'agglomération ?Ce document reprend dans sa totalité les interventions de la journée sur ces thèmes
Quantitative spectral quality assessment technique validated using intraoperative in vivo Raman spectroscopy measurements
Significance: Ensuring spectral quality is prerequisite to Raman spectroscopy applied to surgery. This is because the inclusion of poor-quality spectra in the training phase of Raman-based pathology detection models can compromise prediction robustness and generalizability to new data. Currently, there exists no quantitative spectral quality assessment technique that can be used to either reject low-quality data points in existing Raman datasets based on spectral morphology or, perhaps more importantly, to optimize the in vivo data acquisition process to ensure minimal spectral quality standards are met.
Aim: To develop a quantitative method evaluating Raman signal quality based on the variance associated with stochastic noise in important tissue bands, including C─C stretch, CH2 / CH3 deformation, and the amide bands.
Approach: A single-point hand-held Raman spectroscopy probe system was used to acquire 315 spectra from 44 brain cancer patients. All measurements were classified as either high or low quality based on visual assessment (qualitative) and using a quantitative quality factor (QF) metric. Receiver-operator-characteristic (ROC) analyses were performed to evaluate the performance of the quantitative metric to assess spectral quality and improve cancer detection accuracy.
Results: The method can separate high- and low-quality spectra with a sensitivity of 89% and a specificity of 90% which is shown to increase cancer detection sensitivity and specificity by up to 20% and 12%, respectively.
Conclusions: The QF threshold is effective in stratifying spectra in terms of spectral quality and the observed false negatives and false positives can be linked to limitations of qualitative spectral quality assessment
Frequent EGFR Positivity and Overexpression in High-Grade Areas of Human MPNSTs
Malignant peripheral nerve sheath tumours (MPNSTs) are highly malignant and resistant. Transformation might implicate up regulation of epidermal growth factor receptor (EGFR). Fifty-two MPNST samples were studied for EGFR, Ki-67, p53, and survivin expression by immunohistochemistry and for EGFR amplification by in situ hybridization. Results were correlated with clinical data. EGFR RNA was also quantified by RT-PCR in 20 other MPNSTs and 14 dermal neurofibromas. Half of the patients had a neurofibromatosis type 1 (NF1). EGFR expression, detected in 86% of MPNSTs, was more frequent in NF1 specimens and closely associated with high-grade and p53-positive areas. MPNSTs expressed more EGFR transcripts than neurofibromas. No amplification of EGFR locus was observed. NF1 status was the only prognostic factor in multivariate analysis, with median survivals of 18 and 43 months for patients with or without NF1. Finally, EGFR might become a new target for MPNSTs treatment, especially in NF1-associated MPNSTs
The stress-energy tensor for trans-Planckian cosmology
This article presents the derivation of the stress-energy tensor of a free
scalar field with a general non-linear dispersion relation in curved spacetime.
This dispersion relation is used as a phenomelogical description of the short
distance structure of spacetime following the conventional approach of
trans-Planckian modes in black hole physics and in cosmology. This
stress-energy tensor is then used to discuss both the equation of state of
trans-Planckian modes in cosmology and the magnitude of their backreaction
during inflation. It is shown that gravitational waves of trans-Planckian
momenta but subhorizon frequencies cannot account for the form of cosmic vacuum
energy density observed at present, contrary to a recent claim. The
backreaction effects during inflation are confirmed to be important and generic
for those dispersion relations that are liable to induce changes in the power
spectrum of metric fluctuations. Finally, it is shown that in pure de Sitter
inflation there is no modification of the power spectrum except for a possible
magnification of its overall amplitude independently of the dispersion
relation.Comment: 18 pages, 2 figures. Version to appear in PRD (minor modifications
Targeted proteomics links virulence factor expression with clinical severity in staphylococcal pneumonia
IntroductionThe bacterial pathogen Staphylococcus aureus harbors numerous virulence factors that impact infection severity. Beyond virulence gene presence or absence, the expression level of virulence proteins is known to vary across S. aureus lineages and isolates. However, the impact of expression level on severity is poorly understood due to the lack of high-throughput quantification methods of virulence proteins.MethodsWe present a targeted proteomic approach able to monitor 42 staphylococcal proteins in a single experiment. Using this approach, we compared the quantitative virulomes of 136 S. aureus isolates from a nationwide cohort of French patients with severe community-acquired staphylococcal pneumonia, all requiring intensive care. We used multivariable regression models adjusted for patient baseline health (Charlson comorbidity score) to identify the virulence factors whose in vitro expression level predicted pneumonia severity markers, namely leukopenia and hemoptysis, as well as patient survival.ResultsWe found that leukopenia was predicted by higher expression of HlgB, Nuc, and Tsst-1 and lower expression of BlaI and HlgC, while hemoptysis was predicted by higher expression of BlaZ and HlgB and lower expression of HlgC. Strikingly, mortality was independently predicted in a dose-dependent fashion by a single phage-encoded virulence factor, the Panton-Valentine leucocidin (PVL), both in logistic (OR 1.28; 95%CI[1.02;1.60]) and survival (HR 1.15; 95%CI[1.02;1.30]) regression models.DiscussionThese findings demonstrate that the in vitro expression level of virulence factors can be correlated with infection severity using targeted proteomics, a method that may be adapted to other bacterial pathogens
Responses to hydric stress in the seed-borne necrotrophic fungus Alternaria brassicicola
Alternaria brassicicola is a necrotrophic fungus causing black spot disease and is an economically important seed-borne pathogen of cultivated brassicas. Seed transmission is a crucial component of its parasitic cycle as it promotes long-term survival and dispersal. Recent studies, conducted with the Arabidopsis thaliana/A. brassicicola pathosystem, showed that the level of susceptibility of the fungus to water stress strongly influenced its seed transmission ability. In this study, we gained further insights into the mechanisms involved in the seed infection process by analyzing the transcriptomic and metabolomic responses of germinated spores of A. brassicicola exposed to water stress. Then, the repertoire of putative hydrophilins, a group of proteins that are assumed to be involved in cellular dehydration tolerance, was established in A. brassicicola based on the expression data and additional structural and biochemical criteria. Phenotyping of single deletion mutants deficient for fungal hydrophilin-like proteins showed that they were affected in their transmission to A. thaliana seeds, although their aggressiveness on host vegetative tissues remained intact
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